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From: "jiangchuanganghw at outlook dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug ipa/112783] core dump on libxo when function is inlined
Date: Fri, 05 Jan 2024 03:09:06 +0000 [thread overview]
Message-ID: <bug-112783-4-onewEgqHB9@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-112783-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112783
Jiang ChuanGang <jiangchuanganghw at outlook dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jiangchuanganghw at outlook dot co
| |m
--- Comment #9 from Jiang ChuanGang <jiangchuanganghw at outlook dot com> ---
(In reply to Andrew Pinski from comment #3)
> The problem is not in GCC but rather a bad assumption on the code part.
>
> Basically we have:
>
> memcpy(nbuf, name, nlen);
> ...
>
>
> if (!name)
> ...
>
>
> But the check after a memcpy can be removed as passing a null pointer to
> memcpy is undefined even if nlen is 0 here.
>
>
> This patch to the sources fixes the issue for me:
> ```
> diff --git a/libxo/libxo.c b/libxo/libxo.c
> index 916a111..ea71723 100644
> --- a/libxo/libxo.c
> +++ b/libxo/libxo.c
> @@ -4300,7 +4300,8 @@ xo_format_value (xo_handle_t *xop, const char *name,
> ssize_t nlen,
> if ((xsp->xs_flags & (XSF_EMIT | XSF_EMIT_KEY))
> || !(xsp->xs_flags & XSF_EMIT_LEAF_LIST)) {
> char nbuf[nlen + 1];
> - memcpy(nbuf, name, nlen);
> + if (name)
> + memcpy(nbuf, name, nlen);
> nbuf[nlen] = '\0';
>
> ssize_t rc = xo_transition(xop, 0, nbuf, XSS_EMIT_LEAF_LIST);
> @@ -4324,7 +4325,8 @@ xo_format_value (xo_handle_t *xop, const char *name,
> ssize_t nlen,
>
> } else if (!(xsp->xs_flags & XSF_EMIT_KEY)) {
> char nbuf[nlen + 1];
> - memcpy(nbuf, name, nlen);
> + if (name)
> + memcpy(nbuf, name, nlen);
> nbuf[nlen] = '\0';
>
> ssize_t rc = xo_transition(xop, 0, nbuf, XSS_EMIT);
> @@ -4342,7 +4344,8 @@ xo_format_value (xo_handle_t *xop, const char *name,
> ssize_t nlen,
> if ((xsp->xs_flags & XSF_EMIT_LEAF_LIST)
> || !(xsp->xs_flags & XSF_EMIT)) {
> char nbuf[nlen + 1];
> - memcpy(nbuf, name, nlen);
> + if (name)
> + memcpy(nbuf, name, nlen);
> nbuf[nlen] = '\0';
>
> ssize_t rc = xo_transition(xop, 0, nbuf, XSS_EMIT);
>
> ```
I've encountered the same bug, and your solution does fix it.
But strangely enough, I can't reproduce it with code like the following.
The inevitable condition of this bug still puzzles me. Do you have any thoughts
on this.
#include <stdio.h>
#include <string.h>
static const char *xo_xml_leader_len(const char *name, int len)
{
if (name == NULL || name[0] == '_')
return "";
return "_";
}
void test()
{
char *name = NULL;
int len = 0;
char mbuf[len + 1];
memcpy(mbuf, name, len);
mbuf[len] = '\0';
const char *leader = xo_xml_leader_len(name, len);
printf("leader: %s", leader);
}
int main()
{
test();
return 0;
}
next prev parent reply other threads:[~2024-01-05 3:09 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-30 13:32 [Bug ipa/112783] New: " yancheng.li at foxmail dot com
2023-12-01 5:06 ` [Bug ipa/112783] " sjames at gcc dot gnu.org
2023-12-01 23:33 ` pinskia at gcc dot gnu.org
2023-12-01 23:53 ` pinskia at gcc dot gnu.org
2023-12-12 3:40 ` yancheng.li at foxmail dot com
2023-12-12 3:45 ` pinskia at gcc dot gnu.org
2023-12-12 3:45 ` pinskia at gcc dot gnu.org
2023-12-15 21:09 ` cvs-commit at gcc dot gnu.org
2023-12-15 21:15 ` jvdelisle at gcc dot gnu.org
2024-01-05 3:09 ` jiangchuanganghw at outlook dot com [this message]
2024-01-05 14:38 ` xry111 at gcc dot gnu.org
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